#include<bits/stdc++.h>
using namespace std;
#define N 50005
#define B 225
int F1[B+5][N],F2[B+5][N];
int n,m;
int a[N],sum[N],temp[N];
void precalc()
{
    for(int i=0;i<B;i++){
        int l=i*B;
        if(l>n)
            break;
        for(int r=l;r<=n;r++)
            temp[sum[r]]=-1;

        int tmp=0;

        for(int r=l;r<=n;r++){
            if(temp[sum[r]]==-1){
                temp[sum[r]]=r;
            }
            else
                tmp=max(tmp,r-temp[sum[r]]);
            F1[i][r]=tmp;
           // printf("%d %d = %d\n",i,r,tmp);
        }
    }
    for(int i=0;i<B;i++){
        int r=i*B;
        if(r>n)
            break;
        int tmp=0;
        for(int l=0;l<r;l++){
            temp[sum[l]]=-1;
        }
        for(int l=r-1;l>=0;l--){
            if(temp[sum[l]]==-1)
                temp[sum[l]]=l;
            else
                tmp=max(tmp,temp[sum[l]]-l);
            F2[i][l]=tmp;
           // printf("%d %d = %d\n",i,l,tmp);
        }
    }
}
int solve(int l,int r)
{
    int ll=(l+B-1)/B;
    int rr=r/B;
    int ans=0;
    if(ll<rr){
     printf("%d %d\n",ll,rr);
    ans=max(ans,max(F1[ll][r],F2[rr][l-1]));
    printf("%d %d\n",F1[ll][r],F2[rr][l-1]);
    for(int i=l-1;i<=ll*B;i++)
        temp[sum[i]]=-1;
    for(int i=l-1;i<=ll*B;i++){
        if(temp[sum[i]]==-1){
            temp[sum[i]]=i;
        }
    }
    for(int i=r;i>=rr*B;i--){
        if(temp[sum[i]]!=-1)
        ans=max(ans,i-temp[sum[i]]);
    }
    }
    else
    {
        for(int i=l-1;i<=r;i++)
            temp[sum[i]]=-1;
        int tmp=0;
        for(int i=l-1;i<=r;i++){
            if(temp[sum[i]]==-1)
                temp[sum[i]]=i;
            else
                tmp=max(tmp,i-temp[sum[i]]);
        }
        ans=tmp;
    }
    return ans;
}
int main()
{
    //freopen("input.txt","r",stdin);
    //freopen("output1.txt","w",stdout);
    scanf("%d %d",&n,&m);
    for(int i=1;i<=n;i++){
        scanf("%d",&a[i]);
        sum[i]=sum[i-1]+a[i];
    }
    precalc();
    while(m--){
        int l,r;
        scanf("%d %d",&l,&r);
        if(l>r)
            swap(l,r);
        int ans=solve(l,r);
        printf("%d\n",ans);
    }
}